ANALYSIS OF MUTAGENESIS IN APICAL MERISTEMS OF ROOTS Zea mays L. (POACEAE) INDUCED BY COMBINED ACTION THE IONS OF CADMIUM, NICKEL AND ZINC

Abstract

The paper presents the results of the carried out cytological analysis
of apical meristems of the corn roots of the Blitz 160 MB hybrid in the
presence of zinc, nickel and cadmium ions in the growing medium. It was
found that the combined action of heavy metal ions, first of all, caused a
general decrease in the mitotic index and an increase in the proportion of
cells at the prophase and metaphase stages in the meristematic cells of Z.
mays seedlings. In contrast, the percentage of anaphase cells decreased by
15–20%, and the percentage of telophase cells decreased by 1.2–1.5 times
relative to the control conditions, respectively. In the spectrum of cytogenetic
disorders caused by the action of heavy metals in the roots of the Blitz
160 MB corn hybrid, anomalies caused by damage to chromosomes (single
and multiple bridges, agglutination of chromosomes) and anomalies caused
by damage to the mitotic apparatus (lagging and advancing chromosomes,
disoriented chromosomes, fragments chromosomes and multipolar mitoses).
Compared to the control, the presence of cadmium, zinc and nickel ions in the
growing medium at both minimum and maximum concentrations had a high
cytotoxic effect and induced an increase in the number of aberrant cells in the
meristems of corn roots by more than 5 times. In general, among chromosomal
aberrations, the most common were lagging chromosomes (more than 75% of
the total number of mitotic pathologies), single bridges (8.8%), premature
chromosome movement (2.5%) and multipolarity (2.0%). In addition, the
combined action of metal ions induced the formation of abnormalities such
as agglutination, disoriented chromosomes, and the formation of chromosome
fragments. The general decrease in the mitotic index and a wide range of
chromosomal aberrations established by us indicate that heavy metals, when
they act together, are clastogenic and affect chromosomes at the DNA level.
And the high cytogenetic activity of cadmium, zinc and nickel ions shown by us
confirms the genetic danger of industrial emissions with the content of heavy
metal ions for organisms in ecosystems and provides for the need to develop
a national program for large-scale genetic monitoring of technogenic pollution
of Ukrainian territories.